1. Technical Field
The present invention relates in general to perpendicular recording media, including continuous and patterned recording media, and in particular, to an improved system, method and apparatus for perpendicular recording media with sublayers of dual oxide dopant magnetic materials.
2. Description of the Related Art
Hard disk drives provide data storage for data processing systems in computers and servers. Disk drives are also becoming increasingly pervasive in media players, digital recorders, and other personal devices. Advances in disk drive technology have made it possible for a user to store an immense amount of digital information on an increasingly small disk, and to selectively retrieve and alter portions of such information almost instantaneously. Particularly, recent developments have simplified disk drive manufacturing while yielding increased track densities, thus promoting increased data storage capabilities at reduced costs.
Hard disk drives rotate high precision media, such as an aluminum or glass disk coated on both sides with thin films, to store information in the form of magnetic patterns. Electromagnetic read/write heads suspended or floating only fractions of micro inches above the disk are used to either record information onto the thin film media, or read information from it.
A read/write head may write information to the disk by creating an electromagnetic field to orient a cluster of magnetic grains, known as a bit, in one direction or the other. In longitudinal magnetic recording media applications, a magnetic recording layer has a magnetic c-axis (or easy axis) parallel to the disk plane. As the disk drive industry is transitioning to perpendicular recording technology, adjustments are being made to adapt the disk media so that the magnetic easy axis (crystallographic c-axis) of the cobalt alloy recording layers grow perpendicular to the disk plane. Hexagonal Close Packed (HCP) cobalt alloys are typically used as a magnetic recording layer for perpendicular recording. Some media manufacturers rely on a cobalt alloy with the incorporation of an oxide segregant to promote the formation of small and uniform grains.
To read information, magnetic patterns detected by the read/write head are converted into a series of pulses that are sent to the logic circuits to be converted to binary data and processed by the rest of the system. To write information, a write element located on the read/write head generates a magnetic write field that travels vertically through the magnetic recording layer and returns to the write element through a soft underlayer. In this manner, the write element magnetizes vertical regions, or bits, in the magnetic recording layer. Because of the easy axis orientation, each of these bits has a magnetization that points in a direction substantially perpendicular to the media surface. To increase the capacity of disk drives, manufacturers are continually striving to reduce the size of bits and the grains that comprise the bits.
The ability of individual magnetic grains to be magnetized in one direction or the other, however, poses problems where grains are extremely small. The superparamagnetic effect results when the product of a grain's volume (V) and its anisotropy energy (Ku) fall below a certain value such that the magnetization of that grain may flip spontaneously due to thermal excitations. Where this occurs, data stored on the disk is corrupted. Thus, while it is desirable to make smaller grains to support higher density recording with less noise, grain miniaturization is inherently limited by the superparamagnetic effect. To maintain thermal stability of the magnetic grains, material with high Ku may be used for the magnetic layer. However, material with a high Ku requires a stronger magnetic field to reverse the magnetic moment. Thus, the ability of the write head to write on magnetic material may be reduced where the magnetic layer has a high Ku value.
As shown in FIG. 1, the perpendicular magnetic recording medium 11 is generally formed with a substrate 13, adhesion 15, a soft magnetic underlayer(s) (SUL) 17, a seed layer(s) 19, an underlayer(s) 21, one or more magnetic layers 23, and one or more protective layers 25 for protecting the surface of the perpendicular magnetic recording layer. The perpendicular magnetic recording layer 27 itself comprises a single oxide dopant magnetic layer 27a, and a dual oxide dopant magnetic layer 27b. The performance of the recording layer is important for efficient recording.
Accordingly, a need exists for a practical, attainable apparatus, system, and method for improving the perpendicular magnetic recording layer. Beneficially, such an apparatus, system and method would increase the recording performance of the system. Such apparatuses, systems and methods are disclosed and claimed herein. Further, the perpendicular magnetic recording layers should be able to resist corrosion.